Circuit for resetting an elevator safety chain

Abstract

A circuit ( 34 ) for resetting a component ( 21 ) within an elevator safety chain ( 23 ). The reset circuit ( 24 ) comprises a first reset switch ( 31 ), a second reset switch ( 32 ) and a door contact ( 33 ). This first reset switch is mountable within an elevator shaft ( 2 ) and the second reset switch ( 32 ) is mountable outside the elevator. Preferably, the second reset switch ( 32 ) is hidden from members of the general public but is accessible to an elevator technician. The door contact ( 33 ) is mountable alongside the landing door ( 13 ). The first reset switch ( 31 ), the second reset switch ( 32 ) and the door contact ( 33 ) are arranged in series so that all must be closed to reset the component ( 21 ) whereby, upon activation, the first reset switch ( 31 ) remains closed for a first predetermined time period (Δt 1 ) after which it returns to its open state.

The invention claimed is: 
     
       1. A circuit for resetting a component within an elevator safety chain comprising:
 a first reset switch mountable within an elevator shaft; and 
 a door contact mountable alongside a landing door; 
 wherein the first reset switch and the door contact are arranged in series so that both must be closed to reset the component, and configured such that upon activation, the first reset switch remains closed for a first predetermined time period after which the first reset switch returns to an open state. 
 
     
     
       2. A circuit according to  claim 1 , wherein the first reset switch is accessible from a landing when the landing door is open. 
     
     
       3. A circuit according to  claim 1 , wherein the first reset switch is mountable above the landing door. 
     
     
       4. A circuit according to  claim 1 , wherein the first reset switch is an interval delay relay. 
     
     
       5. A circuit according to  claim 1 , wherein the first predetermined time period is greater than a time taken for the landing door to close automatically. 
     
     
       6. A circuit according to  claim 1 , wherein the first predetermined time period is less than five seconds. 
     
     
       7. A circuit according to  claim 1  further comprising a second reset switch mountable external to the elevator shaft and arranged in series with the first reset switch and the door contact. 
     
     
       8. A circuit according to  claim 1 , wherein the first predetermined time period is less than ten seconds. 
     
     
       9. An elevator comprising:
 a car vertically displaceable within a shaft, 
 a plurality of landing doors; 
 a safety chain; and 
 a reset circuit in accordance with  claim 1 , 
 wherein, in response to opening one of the plurality of landing doors at a particular level while the car is not present at that level, the safety chain is broken and the car is prevented from further travel. 
 
     
     
       10. An elevator according to  claim 9 , wherein the first reset switch is mounted to a door frame.